The countdown has begun for the XB-1’s “historic” first supersonic test flight that should break the sound barrier, according to Boom Supersonic.

Boom’s XB-1 jet breaks sound barrier on first supersonic flight - Boom’s inaugural XB-1 supersonic test flight reached speeds of more than 850 miles per hour

Colorado-based Boom Supersonic plans to build the Overture airliner, which it says will carry as many as 80 passengers while moving at about twice the speed of today’s subsonic airliners.